Re-introduction of the threatened Cocos buff- banded rail to the southern atoll of the Cocos (Keeling) islands, Australia

Summary

The Cocos buff-banded rail (Gallirallus philippensis andrewsi), an Endangered subspecies confined by the 1990s to about 800 birds on a single one-square-kilometre island, Pulu Keeling, in Australia's remote Cocos (Keeling) Islands, was the subject of a national recovery plan's top priority action: establishing a second population elsewhere on the southern atoll. Parks Australia spent years building support from the Cocos (Keeling) community, who own all potential release islands, before selecting the predator-free Horsburgh Island for its intact vegetation and absence of black rats and cats. In April 2013, 39 rails were captured on Pulu Keeling, colour-banded, and transported by swimmers through breaking surf in watertight containers to boats, since fringing reefs prevent any landing craft docking at the source island; all 39 survived release. Monitoring combining radio-tracking, camera traps and transect density estimates found no short-term mortality, first detected wild-hatched chicks within five months, and tracked the population through an initial dip to 23 birds by early 2014 before it rebounded to 54 by October 2014 and 122 by mid-2015, roughly a 300% increase over 26 months; some individuals also dispersed naturally to nearby islands. Monitoring of the source population on Pulu Keeling showed no decline from the capture of founders. Remaining constraints include the group's limited total land area and ongoing biosecurity risk, and the need to eradicate rats and cats from further islands before the rail can spread naturally beyond Horsburgh. The project rates itself successful, crediting a well-resourced, community-endorsed recovery-plan process and a strong, rapid population response once predator threats were removed from the release site.